[Haskell-cafe] Strange encoding issue with Text and Servant

Nigel Rantor wiggly at wiggly.org
Sat Jan 14 18:47:02 UTC 2017

On 14/01/17 17:37, Jan von Löwenstein wrote:
> Oh, it happens with servant on the client side.
> I use a swagger-codegen generated servant based client to access kubernetes.
> Calling https://github.com/soundcloud/haskell-kubernetes/blob/master/lib/Kubernetes/Api/ApivApi.hs#L475 works
> Calling https://github.com/soundcloud/haskell-kubernetes/blob/master/lib/Kubernetes/Api/ApivApi.hs#L473 doesn't.
> From what I see the `QueryParam"labelSelector" Text`is the same in both.
> Logging the value gives the literal `=` as expected. Logging the
> (http-client) requests shows the difference.

So I went ahead and wrote a simple client by hand and when I call the 
two functions on a local endpoint that shows me the request URL I get 
the following.

Same arguments for 'pretty' and 'labelSelector' in both cases.


runListSecret :: Manager -> BaseUrl -> ClientM SecretList 

runListSecret manager baseUrl = listSecret (Just "prettyArg") (Just "=") 
Nothing Nothing Nothing Nothing manager baseUrl 


runListService :: Manager -> BaseUrl -> ClientM ServiceList 

runListService manager baseUrl = listService (Just "prettyArg") (Just 
"=") Nothing Nothing Nothing Nothing manager baseUrl

Server log: - - [14/Jan/2017:18:39:49 +0000] "GET 
/api/v1/secrets?pretty=prettyArg&labelSelector=%3D HTTP/1.1" 404 - 0.0003 - - [14/Jan/2017:18:39:49 +0000] "GET 
/api/v1/services?pretty=prettyArg&labelSelector=%3D HTTP/1.1" 404 - 0.0003

I haven't used swagger-codegen but the servant-client code works for me 
so I would look more into that.

Swagger codegen looks like it might take me a while to get my head into 
so maybe you could look at the generated code, or sling it to me here or 

The two calls are so similar that I can't see why the generated client 
would behave differently in those cases.



> Best
> Jan
> Nigel Rantor <wiggly at wiggly.org <mailto:wiggly at wiggly.org>> schrieb am
> Sa., 14. Jan. 2017 um 18:11 Uhr:
>     On 13/01/17 19:28, Jan von Löwenstein wrote:
>     > Hi,
>     >
>     > I have got a two places with a `QueryParam "q" Text` and call it
>     with a
>     > Text that contains a `=` literal. In one place the `=` is correctly
>     > encoded as %3D, in the other I see a `!D(MISSING)`.
>     >
>     > This has to happen somewhere in Servant or the lower layers. Both
>     Texts
>     > print out nicely with an `=` sign if I just print them to stdout.
>     >
>     > Google does not find `!D(MISSING)` anywhere.
>     >
>     > Any idea what could possibly be the problem here?
>     It would be really useful to see exactly how you are 'calling' this.
>     Do you have a curl command line or are you using some other client?
>        n
>     _______________________________________________
>     Haskell-Cafe mailing list
>     To (un)subscribe, modify options or view archives go to:
>     http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
>     Only members subscribed via the mailman list are allowed to post.

More information about the Haskell-Cafe mailing list